Speed First, Mileage Can Wait
Another plus for a 10K training program to kick off your season—or build fitness in the offseason—is the fact that mileage isn't required. Long training runs might fill you up with wonderful endorphins, but they also beat you down. The consistent pounding, week after week, eventually dulls your fitness and hampers your ability to do speed work normally associated with 10K training.
Over the course of an eight-week 10K training program, you can see upwards of a one to three minute improvement. That's as much as 30 seconds per mile on your functional threshold pace. Now when you begin to do your longer marathon-focused mileage, your easy pace will also see similar improvements.
Consider it an alternative to the constant mileage of marathon training. A 10K program will provide a welcome respite from the traditional mileage oriented training programs. Done properly you'll not only get a mental break, but a physical boost as well.
Speed vs. Distance: The Injury Conundrum
The biggest concern around any speed work is the potential risk for injury. There's no doubt that running with intensity poses a risk, but experience has shown that runners have as much to fear from consistent long runs (more than an hour) as they do from the shorter, harder workouts—if not more.
This is especially true when you consider a program that uses the results of your own 10K time as a guide for determining your training paces. This way, you will only run as fast as your body says it can instead of what a program or coach tells you.
Faster running does have its upside as well. In addition to recruiting those fast twitch muscle fibers, you'll be working at a faster cadence which can serve to improve your running form. And let's not forget the rush of flying down the road.
When to Pull the Marathon Trigger
Before you go and register for the next available marathon, keep a few things in mind. You'll still need a quality training program for at least 12 weeks before your race, if not longer. And you'll ideally have been running pain- and injury-free for a few months. In this way, you should consider the 10K to be your ticket to year-round fitness and speed. It's safe enough to train and race repeatedly, and it's close enough to its marathon cousin to be part of the running foundation that sets you up to achieve your long-distance running goals as well.